1. Cell Structure and Function
AP Biology

2. Activities of Life
Most everything you think of a whole organism needing to do, must be done on the cellular level…
Reproduction
Growth and development
Energy utilization
Response to environment
Homeostasis
AP Biology

3. Cell Characteristics What do all cell types have?
Plasma membrane
Cytosol
Chromosomes
Ribosomes
What organelles are found only in animal cells?
Lysosomes
Centrosomes
What organelles are found only in plant cells?
Cell wall
Vacuole
Plasmodesmata
Chloroplast
AP Biology

4. Types of Cells Prokaryote Eukaryote DNA in nucleoid region
No nuclear membrane separating DNA from rest of cell
No organelles made of membranes
Eukaryote
Chromosomes in nucleus
Chromosomes enclosed in nuclear membrane
Membrane bound organelles present (compartmentalization)
AP Biology

5. Limits to cell size Lower limit Upper limit
Smallest bacteria, mycoplasm
0.1 to 1.0 microns
Upper limit
Eukaryotic cells
microns
Micron = micrometer = 1/1,000,000 meter
Diameter of human hair = 20 microns
AP Biology

6. Surface area increases while total volume remains constant
Fig. 6-8
Surface area increases while
total volume remains constant 5 1 1
Total surface area
[Sum of the surface areas
(height  width) of all boxes
sides  number of boxes] 6
150
750
Total volume
[height  width  length 
number of boxes] 1
125
125
Surface-to-volume
(S-to-V) ratio
[surface area ÷ volume] 6
1.2 6

7. What limits cell size? Surface area to volume ratio
As cell gets bigger
volume increases faster than surface area
Smaller objects have greater surface area to volume ratios
AP Biology

8. Limits to cell size Metabolic requirements set upper limit
large cells, cannot move material in and out of cell fast enough to support life
What process is this? aa O2 O2
CHO
CHO
CHO aa
NH3
NH3 O2
CHO aa aa O2
NH3 aa O2
What’s the solution?
AP Biology

9. How to get bigger?
Become multi cellular (cell divides)
AP Biology

10. Cell membrane Exchange organelle Functions as a selective barrier
Allows passage of oxygen, nutrients and wastes
AP Biology

11. Organelles and Internal Membranes
In eukaryotic cells, internal membranes:
Partition cell into compartments
Create different local environments
Compartmentalize functions
Different structures for specific functions
Unique combination of lipids and proteins
AP Biology

12. Endomembrane System
Play key role in synthesis (& hydrolysis) of macromolecules in cell
Organelles
Endoplasmic reticulum
Golgi apparatus
Lysosomes (animals only)
Vacuoles (plants only)
Vesicles
Pay attention to
How structure relates to function
Cell type in which you would typically find structures
What happens if organelle is not functioning correctly
AP Biology

13. Fig
Nucleus
Rough ER
Smooth ER
Plasma membrane

14. Nucleus Rough ER Smooth ER cis Golgi Plasma membrane trans Golgi
Fig
Nucleus
Rough ER
Smooth ER
cis Golgi
Plasma membrane
trans Golgi

15. Nucleus Rough ER Smooth ER cis Golgi Plasma membrane trans Golgi
Fig
Nucleus
Rough ER
Smooth ER
cis Golgi
Plasma membrane
trans Golgi

16. Peroxisomes Other digestive enzyme sacs
Found in plant and animal cells
Break down fatty acids into sugars
Easier to transport and use sugar as energy source
Detoxifies cell
Alcohol and other poisons
Produces hydrogen peroxide (H2O2)
Waste product
Harmful to cell
Must be broken down to H2O
AP Biology

17. Apoptosis Programmed Cell death
Occurs when digestive enzymes from lysosomes or peroxisomes are released into cell
Critical role in programmed destruction of cells in multicellular organisms
Some cells have to die in an organized fashion, especially during development
Cancer over rides this to enable tumor growth
AP Biology

18. Theory of Endosymbiosis
mitochondrion
internal membrane system
aerobic bacterium
Ancestral eukaryotic cell
Eukaryotic cell with
mitochondrion
Paramecium & symbiont Chlorella
photosynthetic bacterium
chloroplast
AP Biology
Eukaryotic cell with chloroplasts

19. Cell Specializations
What would be the function of a cell with the following properties?
Large number of mitochondria
Large amount of RER, SER and Golgi
Absence of mitochondria, RER, SER, Golgi
Absence of nucleus
Presence of Chloroplast
Large, flattened cell
Elongated cell with many extensions
Flagella, nucleus and mitochondria
Large number of ribosomes
AP Biology